JPS5939155A - Speaker horn device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to telephones, and more particularly to hands-free speakerphone systems.

Speaker horns have advantages over ordinary telephones. For example, you don't have to hold a handset, so you can free up your hands to do other things. Additionally, speaker horns allow multiple people to conduct a conference call at the same time via a single speaker horn.

According to the present invention, the direction of the signal is determined, and the signal from the microphone (originating or sending signal) in the path to the loudspeaker is canceled, while the connection path between the loudspeaker and the telephone line is left intact. This provides a speaker horn with circuitry to prevent microphone-to-loudspeaker feedback. Determining the level of the signal going to the loudspeaker, and determining the determined signal level and/or signal direction (outgoing or incoming)
Accordingly, a control circuit is provided which automatically increases or decreases the gain of the microphone or loudspeaker amplifier by shunting. By means of the cancellation and shunting means, the signal from the loudspeaker is reduced to a minimum level and the reception level of the receiver circuit is ensured at a good level without the need for shunting. This circuit allows simultaneous conversations without producing undesirable oscillations or "echoes" due to feedback.

Hereinafter, the present invention will be described in detail with reference to the drawings. The speaker horn shown in the block diagram of FIG. 1 has a transducer 1 to a microphone 12 for generating a transmitted signal and a transducer or loudspeaker 13 for receiving a signal.

The telephone lines L1 and L2 shown are hook switches H81, f
The speaker is connected via the i-stream bridge 14 and transformer T1.
Connected to the horn circuit.

As shown in the diagram, the microphone consists of an amplifier A I , an audio band pass filter F1, a coupling resistor R1, an amplifier A2, and a resistor R.
5 and a coupling circuit consisting of capacitor C2 and a conductor? The delivery path consisting of tM16 is valved and coupled to one end of the secondary winding 17 of the transformer Tl.

The other end of the winding is connected to the negative side of the flow bridge 14 via a resistor R6. The audio signal generates a voltage across resistor R6 via transformer TI.

The junction of resistor R6 and winding 17 is node 1, winding 1%117
Assuming that the junction between the upper end of the conductor 16 and the conductor 16 is a node 2, voltages of the same phase are formed at the nodes 1 and 2 due to the signal emitted from the microphone 12 (output audio signal).

The telephone line is hook switch contact H8-1, rectifier bridge 14, transformer T1, conductor 16, resistor R7, amplifier A6
, resistor R9, amplifier A9, and capacitor C7.

The above sending (outgoing) route and incoming (receiving) route are node 2 (
It is also the junction point of capacitor 2, resistor R7 and conductor 16)
They are together. Therefore, the microphone and loudspeaker are apparently coupled.

Means are provided to electrically separate the microphone and loudspeaker. Specifically, inverting amplifier A4 is coupled to node 1. Let the output of amplifier A4 be node 3. The signal at node 3 is 180° out of phase with the signal at node 1. Therefore, the phase is also shifted by 180° with respect to the transmission signal of node 2.

Note that the received signals occurring at nodes 1 and 2 are further 180° out of phase. Therefore, the received signal at node 3 is approximately in phase with the received signal at node 2.

The signal at node 3 is coupled via resistor R8 to the junction of resistor 7 and amplifier A6. By appropriately selecting the resistance values of resistors R7 and R8, it is possible to almost cancel out the output signal at the input side of amplifier A60.

Conversely, the incoming (received) signals are added at the input side of amplifier A6.

Even if you use a cancellation circuit like coughing, it will not be 100% cancellation. In this example, the line impedance is at node 1
It is one of the factors that determines the line voltage.
Since impedance varies, 100% effective cancellation is not possible.

Therefore, a means is provided to divert undesired microphone signals that have not been canceled out so that they do not enter the loudspeaker 13. Specifically, the output of the amplifier A6 is coupled to the input side of the amplifier A9 via the resistor R9 as described above, but is shunted by the receiving switch means 18 so that this signal does not enter the amplifier A9. The receiver switch means 18 further comprises a resistor RIO which serves to vary the gain of the loudspeaker amplifier means and is connected to the junction of resistor R9 and the input of amplifier A9. The other end of resistor RIO is connected to the negative power supply via coupling capacitor C4 and FET transistor Q2.

When FET l-transistor Q2 is turned on, the gain of the loudspeaker amplifier means is low and the remaining output signal is
It is almost completely removed in the loudspeaker circuit before reaching 9. Therefore, the loudspeaker 13 does not work.

The resistor all connected in parallel with the resistor Q2 is the capacitor C4.
This is to prevent DC voltage from being accumulated in the transistor Q2 (when transistor Q2 is off).

The accumulation of such DC voltages results in a "click" sound when the transistors switch.

Means are provided for reducing the gain of the output signal amplification means. In detail, there is a transmission switch circuit 19, which is
It has a resistor R2 connected to the junction of resistor R1 and the input of amplifier A2. The other end of resistor R2 is capacitor C1
and is connected to the negative power supply via the FET transistor Q1. However, when transistor Q1 turns on,
The outgoing signal is shunted toward the negative power supply. Resistor R3, like resistor R11 in the receiver switch circuit, prevents "click" noise by preventing voltage from building up on capacitor C1 when transistor Q1 is off.

The transmitting switch means and the receiving switch means change the gains of the transmitting amplifying means and the receiving amplifying means, respectively. Such switching means operates to divert or pass at least a portion of the transmitted or received signal depending on whether the signal of the transformer T1 is an outgoing signal or an incoming signal.

For this purpose, means are provided for detecting the direction of the audio signal. Specifically, a voice direction detection circuit 21 is provided. This circuit consists of amplifier A3, inverting amplifiers A4, A5 and e
It consists of an x exclusive OR gate G1.

In transmission mode, the signal of transformer TI is a sending signal,
The audio signal of node 2 is passed through amplifier A3 exclusive
ive is connected to OR gate G1's single-person power. The audio signal at node 1 is connected to the remaining inputs of gate GI via inverting amplifiers A4 and A5. These amplifiers convert audio signals into rectangular signals.

In the transmission mode, the signals 1d of nodes 1 and 2 are in phase, so both signals of gate G1 are in phase, and their output becomes "L".

In the receiving mode, that is, when the signal of the transformer Tl is an incoming signal, the phase of the single input of the gate Gl is opposite, so its output becomes ``H''. In this way, the low level output of the gate 1 causes the transmission A signal is determined to be an incoming signal by a high level output.

A slight phase shift occurs in the input signal of gate G1 due to the telephone line. That is, since the phases of both human input signals do not completely match, a negative spike occurs in the output of gate G1 in the incoming mode. Please refer to the timing charts of the gate Gl shown in FIGS. 2 and 3.

Means are therefore provided to remove these spikes. In particular, the outlet of gate 1 is coupled via resistor R16 to the output of differential level detector A8. Detector A8
Another input of is coupled to a reference level circuit 22. The reference level circuit 22 includes a resistor R1 connected to a negative power supply.
It consists of a parallel circuit of 7 and a capacitor CIO, and a resistor 18 (approximately the same as resistor 17) connected to the positive power supply, and determines a low input level. A capacitor C9 inserted into the input of the detector 6A8 serves to absorb spikes and maintain the output of the detector at the "H" level when there is incoming audio and at the "L" level when there is outgoing audio (second, (See Figure 3)
.

Means are provided for determining the signal level of the loudspeaker amplifier means. Specifically, there is a signal level detection circuit 24, which has a bumper amplifier A7 whose input is connected to the junction between the output of the amplifier A6 and the resistor R9. The output of amplifier A7 is connected to coupling resistor R13, high pass filter F2. It is connected to the power of the DC level detector LDI via the low pass filter F3, the amplifier Al01, and the rectifier/integrator circuit 26. Another input of the DC level detector LDI is coupled to a reference level circuit 27 similar to circuit 22.

Means is provided for shunting the signal to the level determination circuit 24 to the positive power supply. In detail, the level judgment switch means 2B
, which has a capacitor C8 connected to the junction of the low pass filter F2 and the low pass filter F3, and an FET transistor Q3 inserted between the capacitor C8 and the positive power supply. Resistor 15 prevents charge from accumulating in capacitor C8 when transistor Q3 is non-conductive.

Transistor Q3 is switched via resistor R14 in response to the output of gate G2. The output of the gate G2 becomes 'H' level when any of its inputs is low, and it makes a '1L' level when the single power is at the 1H' level. Since the output of the detector A8 is at the 'L' level while the sound is being transmitted, the gate The output of G2 is maintained at "H" (see FIG. 3). Therefore, during transmission, transistor Q3 is on and the output of level detector LDI is maintained at "L".

Means are provided for controlling the receiving and transmitting switch means in response to the output of the level detection circuit 24 and/or the output of the direction detection circuit. In particular, control circuit means 29 are provided, which have a gate G3.

Gate G3 controls timing circuits M1, M2, M3. The timing circuit controls gates G4 and G5, and their respective outputs control the switching of transistors Q2 and G3.

Gate G3 has the power of three people. One input is game)Gl
The second power is connected to the output of the DC level detector LDI, and the third power is connected to the output of the timing circuit, which is a stable timer that generates a 10 millisecond signal at the "L" level. .The gate G3 is an inverted AND gate. Therefore, if any of the input signals becomes "L", it outputs "H". When all the inputs are "H", the output becomes "L".

The timing circuit M1 is not triggered while the output is 1H". During transmission, the output of the circuit LDI is "L". Therefore, the output of game G3 maintains "H".

When the incoming signal is received by transformer T1, gate G1
The output of the detector LD is "H", and since the transistor Q3 is turned off by the "L" level signal from the gate G2, the output of the detector LD is
The output of I also becomes "H" (see Figure 2).

Due to the 1L level output of the gate G3, the timing circuit M1 and its output terminal Q are held high for 200 milliseconds each.
The timing circuit M3 is triggered by the L" level signal from the η terminal and outputs a signal of "1" pulse.
It outputs an "L" level signal for 0 milliseconds. Furthermore, since the "L" level signal from the Q terminal is also given to OR game G5, it outputs the 1z" level of OR game G5 and turns on transistor Q1. and shoot the microphone circuit.

The Q terminal of the circuit M1 provides a 1H" signal to the gate G4.

After 10 milliseconds, gate G4 is activated by timer circuit M3.
“Receives the signal. Therefore, the output of G4 is もH
This %% 111 level output turns off transistor Q2 i/(-L, increasing the gain of the loudspeaker amplifier.

However, timer M1 remains the same for at least 200 milliseconds. Since the output of G5 receives and receives a 2L level signal from circuit M, the output is maintained at 1L.

After 200 milliseconds, if there is no new incoming signal, circuit Ml
The output of the terminal returns to the normal state, that is, the Q terminal is "L" and the terminal (■) is ")". The 5L" level signal at terminal Q triggers timer M2, causing its output to remain low for io milliseconds.
Make it. Because of this "L" signal, the output of gate G5 maintains 8L" for another 10 ms. In this way, timer M2 increases the transmitting gain for about 10 ms (guard time) after the receiving gain decreases. Similarly, timer M3 ensures that the receive gain does not increase for 10 milliseconds after the transmit gain decreases. Such a guard period prevents the generation of "switching" noises during switching.

Means for supplying power to the speaker/horn circuit from the telephone line is provided. In detail, the Zener diode Zl in parallel with the smoothing capacitor C3 is connected to the primary winding 31 of the transformer.
is inserted between the lower end of the rectifying bridge 14 and the negative terminal of the rectifying bridge 14. The upper end of the winding 31 is coupled to the positive terminal of the rectifier bridge 14. The junction of Zener diode z1 and winding 31 is connected to the positive power supply via lead 32. The lower end of the Zener diode Z1 is connected to a negative power supply via a lead wire 33.

Connections between gates G4, G5 and switch circuits 18, 19 are made via respective timing circuits consisting of resistor R12 and capacitor C6, resistor R4 and capacitor C5. This timing circuit has the function of preventing noise such as "one click" at the time of switching.

In this way, the circuit cancels the transmitted signal appearing at the receiving circuit and automatically increases or decreases the gain of the amplifiers in the incoming and outgoing circuits according to the direction and/or level of the signal. Additionally, the circuit provides an effective time guard to effectively eliminate oscillations or "echo" in speaker horn systems.

[Brief explanation of drawings]

Figure 1 is a block diagram of the speaker/horn circuit, Figure 2 is a timing chart of each part in Figure 1 for incoming signals from the telephone line, and Figure 3 is a timing chart for each part in Figure 1 for signals sent to the telephone line. This is a timing chart. 12: Main 13: Loudspeaker 18: Receiving switch circuit 19: Outgoing switch circuit 21: Signal direction detection circuit 24: Signal level detection circuit 28: Signal level judgment switch 29: Control circuit (2 others) ) 1 entry 61 Dingyu ``sweet''``■-G2'' - old'' - 11- FIG 2 'FIG, 3 Procedural amendment (method) February 3, 1920, Office Commissioner Waka Transfer Aifu-dono 1, Indication of the case Showa (2nd year 9i'l-Application No. /I/ltL/l No. 6, Relationship with the case of the person making the amendment) Applicant's address l = Seyu 10 ite, 7 Done , 7, 7, incoho, - te, t. 4. Agent 5, date of amendment order: November 8, 1920 (Showagu')
Shipping date) 6. Subject to correction

Claims (1)

[Claims] (1) Microphone means for generating an outgoing signal, loudspeaker means for converting an incoming signal into a sound wave, and when receiving a signal from a telephone line and transmitting a signal to the telephone line. In a loudspeaker horn apparatus having a telephone, sometimes comprising a circuit for preventing feed banking between the loudspeaker means and the microphone means, said circuit comprises: a first means for varying the magnitude of the signal from the microphone means; 1. A speaker horn device comprising: second means for changing the magnitude of a signal sent to a speaker; and means for controlling said first means and second means according to the direction of the signal. (2. In the speaker horn device according to claim 1, the control means includes direction determining means for determining the direction of the signal. (3) The speaker horn according to claim 2. In the apparatus, the direction determining means includes exclusive OR gate means, circuit means for coupling the outgoing signal to the telephone line so that the outgoing signal is in phase and the incoming signal is out of phase at two different points, and circuit means for connecting the two points. and a means for coupling to the exclusive OR gate circuit so that the output of the gate circuit does not indicate the direction of the signal. (4) In the speaker horn device according to claim 3 , level detecting means is provided, and means is provided for coupling the output of the exclusive OR gate circuit means to the level detecting means in order to determine the direction of the signal, and in response to the output of the level detecting means, the control means The first means and the second means are controlled. (5) In the speaker horn device according to claim 4, the circuit includes a sending amplifying means for amplifying the sending signal and the incoming signal, respectively. and an incoming amplification means, and further,
The first means has first switch means for shunting the outgoing amplifying means, and the second thousandth stage has second switching means for shunting the incoming amplifying means. (6) In the speaker/horn device according to claim 5, the control means includes gate means for providing a signal for activating the switch means. (7) In the speaker horn device according to claim 6, the control means includes timing means for turning on the first and second switch means at different times. (8) In the speaker horn device according to claim 7, the control means provides a time difference between when the first and second switch means are turned off and turned on, respectively. (9) In the speaker horn device according to claim 1, a canceling means is provided for canceling the signal sent from the microphone means to the loudspeaker means. (101) In the speaker horn device according to claim 9, the canceling means includes inverting means for inverting the signal from the microphone means and using this inverted signal to transmit the signal from the microphone means to the loudspeaker means. means for canceling the signal. means for canceling the outgoing signal before it enters the receiving circuit while maintaining electrical connection between the receiving circuit and the telephone line; means for detecting the direction of the signal; and means for detecting the direction of the signal even when the gain is substantially reduced. A speaker horn device comprising: means for changing the gain of the transmitted and received signals according to the direction of the signals so as to enable simultaneous conversation.The speaker according to claim 1. - In the horn device, the canceling means and the signal direction detecting means have a common element. circuit component means such that the signals in the first direction are in phase and the signals in the second direction are out of phase at a point, and the output is high level when there is an out of phase signal on the input side and low when there is an in phase signal on the input side; and gate means for providing a level output. In the apparatus according to claim 13, the circuit component means includes transformer means. (apparatus according to claim 14) wherein the gate means comprises exclusive OR gate means coupled to the upper and lower ends of the secondary of the transformer means.